Spotted Moon Snail or Bladder Moon Snail
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Naticidae, Genus: Polinices, Species: P. mammilla · Naticidae (Moon Snail or Cat's Eye family) · Gastropod; Globose/Spiral shape; Whole shell partially buried in sand.
Species
Polinices mammilla (Likely, 85% confidence based on aperture and dorsal pattern)
Shell Type
Gastropod; Globose/Spiral shape; Whole shell partially buried in sand.
Family
Naticidae (Moon Snail or Cat's Eye family)
Size
Approximately 1-1.5 inches (25-38mm). This is typical for a maturing adult of this genus.
Color & Pattern
External: Creamy white to pale tan base with dense, irregular dark brown or black zig-zag streaks and spots. Internal: Bright yellow-orange to deep egg-yellow coloration visible within the aperture (mouth). The glossy texture suggests a living or very fresh specimen.
Rarity
Common to Very Common across its native range, though the vibrant orange throat remains a prize for beachcombers.
Habitat
Intertidal and shallow subtidal zones. Prefers sandy substrates where it can burrow to hunt prey. Marine environment.
Geographic Range
Indo-Pacific region, extending from East Africa to Polynesia and north to Japan.
Description
A smooth, globose shell characterized by a heavy callous and a wide, semi-circular aperture. The shell is thick and sturdy for its size, with a glossy finish that resists sand abrasion. The most striking feature is the contrast between the dark maculated patterns on the exterior and the warm, sunset-orange interior of the lip and throat.
Key Features
Distinguished by the large, thick umbilical callus that partially or fully fills the umbilicus, and the vibrant orange-yellow staining deep inside the aperture.
Collector Value
Low to Moderate ($2-$10 USD). While common, specimens with intense aperture color and no chips are very popular in 'starter' collections and decorative displays.
Condition Notes
The specimen appears to be in 'Fine' to 'Gem' condition. It is wet and showing high gloss, suggesting it is either still inhabited or very recently washed up. There is no visible sun-bleaching or erosion.
Interesting Facts
Moon snails are predatory carnivores. They use a specialized tongue (radula) and acid to drill perfectly circular 'countersunk' holes into the shells of clams and other snails to eat them. They also produce unique egg cases known as 'sand collars' that look like discarded pieces of rubber or plastic on the beach.
Ecological Role
High-level predator within sandy-bottom communities. They help regulate bivalve populations but have no significant conservation restrictions as they are currently abundant.
Similar Species
Noticarius maculatus (which has more distinct spot rows) and Polinices lacteus (which is typically pure white).
Beach Finding Tips
Look at low tide on sand flats or near seagrass beds. Watch for 'wandering' trails in the sand; the snail often travels just beneath the surface, creating a small mound or 'plow' mark.